Water tube boiler for producing hot water or steam



H. VORKAUF June 7, 1966 WATER TUBE BOILER FOR PRODUCING HOT WATER OR STEAM I Filed Dec. 18, 1963 2 Sheets-Sheet 1 3 I93 Jnrenfor:

Heinrich Vo Ka f By: M lan am Bama z/ H. VORKAUF June 7, 1966 WATER TUBE BOILER FOR PRODUCING HOT WATER 0R STEAM Filed Dec. 18, 1963 2 $heetsSheet 2 l l tlllllll Jnrenfon' Heinrich l/W/(W @HWMKML United States Patent 14 Claims. (61.122435).

This invention relates to water tube boilers, and is relevant to water tube boilers employed for producing steam, as well as to water tube boilers employed for raising the temperature of water to a point below the boil-. ing point thereof.

Conventional water tube boilers are of rectangular or circular cross section. The-internal walls of the boilers are partly or entirely covered with tubes from which other heat exchanging elements may project into the path of flowing heating gases. It is generally desirable to install heat exchanging elements having the greatest possible effective surface in the available boiler space. Because of the cross sectional shapes, full utilization of the available boiler space is not possible in conventional boilers without the use of a multiplicity of difierent sizes and shapes of heat exchanging elements in the same boiler.

The differences in size and shape between the elements are undesirable mainly for two reasons; The heat exchanging elements of different size and shape differ in their heat transfer characteristics. It is practically impossible simultaneously to maintain optimum conditions of heat transfer in a variety of such elements. The manufacture of a boiler including many different parts is relatively costly, diflicult, and time consuming. Automatic operations are applicable only to a very limited extent. Even with the use of different types of heat exchanging elements, the boiler space may not be fully utilized if it is of rectangular or circular cross section.

There are certain applications in which a boiler of rectangular cross section cannot be employed because of limitations of location or intended use. A boiler of round shape may be more adaptable in this respect, but the use of straight boiler tubes in a boiler of round cross section involves the formation of dead pockets between the boiler shell.and the tubes which are arranged in a rectangular bundle. If it is attempted to arrange the heat exchanging surfaces in radical planes to avoid such dead pockets, the several elements which jointly form the radially arranged surfaces must be of different dimensions to fill the cross section available.

It has heretofore been proposed to employ spiralshaped heat exchanging tubes in boilers having a circular 1 cross section. Because of the unfavorable relationship of length and cross section of the flow area in such tubes, they cannot be used in natural convection boilers. The spiral-shaped tubes are relatively costly and diificult to form.

It is generally inconvenient to remove defective heat exchanging elements of conventional water tube boilers for repair. The removal of a defective element frequently requires the previous removal of one or more other elements not themselves requiring repair.

One of the objects of the invention is the provision .of a water tube boiler for heating water or for generat- Patented June 7, 1966 Yet another object is the provision of a boiler in which neither stagnant pockets nor channels of preferred flow are present which would interfere with uniform flow of heating fluid over the cross section of the boiler.

A further object is the provision of a boiler which achieves the above objects without forced flow of water through the tubes, and may rely on natural convection a one.

An additional object is the provision of a boiler in which steam is generated, or water is heated at practically the same rate in each of a multiplicity of heat exchanging elements.

Another object is the provision of a boiler in which the several heat exchanging elements are readily accessible for cleaning, inspection, and repair, and. in which individual elements may readily be removed without disturbing others.

A final object is the provision of a boiler which is effective not only in conjunction with a fuel burner of its own, but which may also be employed to extract thermal energy from waste gases discharged from another apparatus.

With these and other objects in view, the water tube boiler of this invention is provided with an outer wall that defines the boiler space. The latter has'a normally upright axis, and at least an axial portion thereof is of substantially hexagonal cross section. A source of-gaseous heating fluid and means for withdrawing the fluid when spent communicate with respective axial portions of the boiler space. A distributor tube is arranged in one axially terminal portion of the space, and a collector tube is arranged in the other terminal portion, and is normally upwardly spaced from the distributor tube.

These tubeseach essentially consist of six longitudinally consecutive sections which jointly form a closed, substantially regular hexagon. The hexagonally shaped distributor and collector tubes hug the outer boiler wall. The water tubes of the boiler which communicate with the distributor tube and the collector tube are arranged in a portion of the boiler space axially intermediate the afore-mentioned terminal portions, and are ofiset toward the axis of that space from the distributor and collector tubes.

In its more specific aspects, the invention provides for water tubes which are arranged in three columns, each including a plurality of heat exchanging units which extend in respective parallel axial planes. Each heat exchanging unit includes at least one of the water tubes. The planes of the units in the three columns are oflfset from each other by about 60 with respect to the axis of the boiler space.

Other features and many of the advantages of this invention will be readily appreciated as the invention becomes better understood by reference to the following detailed description of preferred embodiments when considered in connection with the accompanying drawings in which:

FIG. 1 shows a boiler of the invention in elevational I on the line II--H;

onal collector tube in vertically spaced alignment with the distributor tube.

Eleven vertical connecting tubes, 3 extend upward from each of the sections 1a, 10, and 1e of the distributor tube, and carry respective distributor manifolds 4 alternatingly arranged in two closely spaced horizontal planes between the collector tube 2 and the distributor tube 1, and nearer to the latter than to the former. The imperforate boiler bottom, not illustrated in detail, and the distributor manifolds 4 vertically define therebetween a combustion chamber 5 which is equipped with an oil burner 6, omitted from FIG. 2 for the sake of clarity.

Fourteen main heat-exchanging tubes 7 extend in a row vertically upward from each manifold 4, and their upper ends communicate with a common collector manifold 8. The collector manifolds attached to tubes communicating with the distributor tube section 1a are connected to the collector tube section 2a by respective vertical connecting tubes 9. The collector manifolds are arranged in two planes which are axially closely adjacent each other. The manifolds 4, 8 associated with the distributor tube section 1a are parallel to each other, to the distributor tube sections 10, 1], and to the collector tube sections 2c, 2 of which the section 20 only is shown in the drawing. The length of each manifold is about equal to that of the parallel distributor tube sections.

The tubes associated with the distributor tube sections and 1e are arranged in a manner analogous to that described hereinabove with reference to the distributor tube section 1a and associated structures.

The boiler space has the shape of a regular hexagonal prism. The distributor tube 1a-1f and the collector tube 2a-2f are arranged along the circumferences at the hexagona-l end faces of the prism. The heat exchanging tubes 7 are uniformly distributed over the cross section of the prismatic space. Each distributor manifold 4, the corresponding fourteen tubes 7, and the associated collector manifold 8 jointly constitute a heat exchanging unit having the overall shape of a flat rectangular plate.

All heat exchanging units are of identical construction and of identical dimensions. The extend'in vertical, axial planes. Adjacently juxtaposed units are axially offset a small distance and the associated connecting tubes 3, 9 slightly differ in length. This arrangement permits un impeded flow of heating gases between the several manifolds which would otherwise form a closed radial wall across the boiler space.

The unit of manifolds 4, 8 and tubes 7 associated with the same distributor tube section extend in planes which are parallel to each other and parallel to a pair of other distributor and collector tube sections. The heat ex- Changing units directly communicating with the distributor tube section 1a thus are parallel to the distributor tube sections 10 and If, those communicating with the section 16 are parallel to the sections 1b and 1e, and those communicating with the section 1e are parallel-to the sections it: and 1d. The units associated with the same sections of the distributor and collector tube jointly form a col umn whose cross section is a rhombus having angles of 60 and 120. The three identical columns are angularly offset 60 relative to each other and jointly occupy the entire boiler space above the combustion chamber 5.

The distributor tube sections 117, 1d and 1f are respectively connected to the corresponding collector tube sections by rows of straight auxiliary heat exchanging tubes 4 with insulating material 17. The boiler wall thus consists of the layer 17 and the shell 16. Unheated return pipes 12 are respectively embedded in the six segmentshaped bodies of insulating material, and directly connect the six collector tube sections to the corresponding distributor tube sections for return of condensate.

The drum 13 provides water for the distributor tube 1 through down pipes 14. Where the return pipes 12 join the several sections of the collector tube, steam lines 15 extend upward from the collector tube, and over to the drum 13. The boiler is open in an axial upward direction, and its top is shaped to be connected to a flue in the conventional manner.

The arrangement of heat exchanging tubes 7 in three columns, each consisting of eleven flat heat-exchanging units, permits the fullest possible utilization of the available boiler space. The heat exchanging surface may be enlarged almost at will by increasing the number of identical units, and by decreasing their thickness. The main heat exchanging units of the boiler are interchangeable. The necessary bending operations may be performed with a single die, and the joints between the elements are of the same type so that they may be made on automatic equipment.

Inspection, maintenance, and repair of the boiler is simple. Virtually all tube surfaces are accessible for cleaning. The units may be individually removed without disturbing other units, and without disturbing the peripherally arranged distributor and collector tubes.

The flow distribution of the heating gases over the cross section of the boiler is practically uniform. Because of the uniformity of the heat exchanging elements and of their arrangement, the fluid within the tubes is heated in substantially the same manner.

The heating gases flow through the boiler in a straight path which is free from restrictions where the gases enter and leave the main heat exchanging space. The boiler may therefore be operated with large amounts of heating gases passing at a high velocity.

The vertical arrangement of the tubes reduces deposits of fly ash and similar pulverulent material which normally drops between the tubes and downwardly out of the main heat exchanging space.

As is evident from FIG. 2, the connecting tubes associated with each column of heat exchanging units are concentrated in a small space which may readily be made accessible for inspection and repairs. If the boiler is operated with forced circulation, the apertured throttling plates conventionally employed in water tube boilers of that type may be located in the readily accessible area for the necessary inspection.

The cylindrical boiler shell is preferred with a hexagonally prismatic tube arrangement of the invention because of its mechanical strength, particularly the high resistance to sudden internal pressure peaks such as may arise during flash combustion of fuel because of malfunctioning of the burner. Cylindrical boiler shells are more readily connected to the usual cylindrical ducts retains most of the advantages of the first-described embodiment of the invention.

The boiler shown in FIG. 3 is closely similar to that described in more detail hereinabove in most aspects, and description will be limited to the distinguishing features of the modified boiler. In addition to the fourteen heat-exchanging units connected to each of the distributing tube sections In, 1c, and 1e, each column of parallel units includes two units connected to the adjacent end of one of the sections 1b, 1d, or 1f. The individual units are identical, but they are shorter in a horizontal plane than the corresponding parallel sections of the distributing tube.

As seen in FIG. 3, the cross section of each column, therefore, has the shape of an elongated parallelogram one end of which has been bent. The hexagonal cross section of the boiler is occupied by evenly spaced heat exchanging tubes 7 except for an axial duct which is centrally arranged between the three columns of heat exchanging units and extends upward from the combus tion space of the boiler to the open top, by-passing the heat-exchanging units.

A valve disk 18 is mounted in the by-pass duct, and is arranged for pivoting movement about a horizontal axis in a manner conventional in itself, and not shown in detail. Movement of the disk 18 about the axis thereof permits the gas flow through the central by-pass duct to be controlled, whereby the steam output of the boiler at constant supply of hot heating gases may be regulated.

The by-pass duct further facilitates access to the heat,

exchanging surfaces of the boiler for inspection, cleaning, and repair of the heat exchanging units without dismantling of the boiler.

An additional embodiment of the invention is shown in FIG. 4- in elevational axial section. The boiler illustrated is intended to utilize the residual heat of waste gases derived from other apparatus not in itself relevant to the invention, and not shown in the drawing. It is conventional to use the waste gases of a gas turbine, of a metallurgical or a ceramic furnace for the production of steam.

The waste heat boiler shown has a water distributing tube 21 of closed hexagonal shape, and a steam collecting tube 22 of the same shape axially spaced from the distributing tube and aligned therewith. The heating fluid is supplied to the boiler from below through a waste gas duct 23 and a conical connector 24. A releasably attached conical connector 25 at the top of the boiler connets the same to a flue, not shown. The boiler shell 26 is cylindrical and insulated in the manner described in detail in connection with the embodiment illustrated in FIGS. 1 and 2.

The several flat heat exchanging units of the boiler of FIG. 4 are arranged in parallel axial planes in the manner illustrated in FIG. 2. A plurality of units jointly constitute a column of rhombic sections, and three columns substantially fill the boiler space. Each unit of the boiler consists of a single length of tubing 27 rising vertically from the associated distributing tube section to a level corresponding to the top of the combustion space 5 in FIG. 1, thence extending horizontally parallel to one pair of the distributing tube sections with which the unit is not directly connected, and upward to the associated collecting tube section in alternating 180 bends and hori zontal runs. 'The several portions of the tubing length 27 extend within a common vertical plane.

A circulating pump 28 draws water from a drum 30 through a down pipe 29, and forces it into the boiler through a feed pipe 31 for forced circulation of Water in the boiler. It will be understood that a feed water supply may be connected to the boiler shown in FIG. 4 at any desired point in a conventional manner, and that steam is withdrawn from the top of the drum 30 as is usual.

When the connector 25 is taken off, the several heat exchanging units of the boiler shown in FIG. 4 can be cleaned, inspected, or removed from above in a particularly convenient manner.

The illustrated and described boilers of the invention may readily be modified to supply hot Water rather than steam. The modification mainly involves the omission of the drums 13, 30, cold water or return connections to 6 the distributor tubes 1, 21, and hot water connections to the collector tubes 2, 22. 7

It should be understood, therefore, that the foregoing disclosure relates to only preferred embodiments of the invention, and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of the disclosure which do not constitute departured from the spirit and scope of the invention set forth in the appended claims.

What I claim is:

1. A water tube boiler comprising, in combination:

(a) wall means defining a boiler space (1) said space having a normally upright axis,

at least a portion of said space being of substantially hexagonal cross section;

(b) a source of a gaseous heating fluid communicating with one axial portion of said boiler space;

(c) means for withdrawing said heating fluid from another axial portion of said boiler space;

(d) a distributor tube in one axially terminal portion of said boiler space;

(e) a collector tube in the other axially terminal portion of said space, and normally upwardly spaced from said distributor tube, y

(1) said collector tube and said distributor tube each having six sections jointly constituting a substantially regular hexagon of tube sections,

(2) said sections being arranged closely adjacent said wall means and spaced from said axis; and

(f) a plurality of water tubes in a portion of said space axially intermediate said terminal portions,

(1) said water tubes being offset from said hexagons of tube sections in a direction toward said axis and communicating with said distributor tube and with said collector tube, and

(2) said water tubes being arranged in three columns, each column including a plurality of heat exchanging units extending in respective parallel axial planes,

(3) each heat exchanging unit including at least one of said water tubes, and the'planes of said columns being ofiset from each other by about 60 with respect to said axis.

2. A boiler as set forth in claim 1, wherein each unit includes a plurality of said water tubes, each tube being straight and having two end portions, and two manifold tube means respectively connecting said end portions to said distributor tube and to said collector tube.

3. A boiler as set forth in claim 1, wherein said one water tube has a plurality of arcuately bent portions and a plurality of straight portions interposed between said bent portions, said portions extending in said plane of the corresponding unit.

4. A boiler as set forth in claim 1, wherein said units are of substantially the same size and shape.

5. A boiler as set forth in claim 1, wherein the Water tubes of each column are connected to a respective section of said distributor tube and to a respective section of said collector tube, the parallel planes of the units of each column being angularly oflset substantially 60 from the connected sections.

6. A boiler as set forth in claim 1, wherein said water tubes are substantially uniformly distributed over said substantially hexagonal cross section of a portion of said boiler space.

7. A boiler as set forth in claim 1, wherein said water tubes define therebetween an axial duct free from said I water tubes, said duct passing through the portion of said boiler space of substantially hexagonal cross section, and said water 'tubes being substantially uniformly distributed over the remainder of said substantially hexagonal cross section.

further comprising a plurality of return pipes, respectively connecting the sections of said collector tube to the corresponding parallel sections of said distributor tube, and thermal insulating means insulating said return pipes from said boiler space.

9. A boiler as set forth in claim 1, wherein said heat exchanging units are axially offset from said distributor tube in an upward direction, and said source of heating fluid is axially interposed between said units and said distributor tube.

10. A boiler as set forth in claim 1, wherein said Wall means include a cylindrical shell coaxial with said boiler space.

11. A boiler as set forth in claim 10, wherein said source of heating fluid includes a cylindrical duct axially joined to said shell for admitting a waste heating gas to said boiler space.

12. A boiler as set forth in claim 1, wherein said heat exchanging units are substantially identical, each unit having the overall shape of a flat plate and including a plurality of water tubes spacedly juxtaposed in substantially parallel alignment, and two manifold means connecting respective end portions of said water tubes to each other and to said distributor tube and to said collector tube respectively.

13. A boiler as set forth in claim 12, wherein the 'planes of each column are substantially parallel to two sections of each of said hexagons.

14. A boileras set forth in claim 1, wherein each unit has the overall shape of a fiat plate and includes a water tube having consecutive straight and arcuate portions, said portions extending in a common axial plane.

References Cited by the Examiner UNITED STATES PATENTS 1,793,867 2/1931 Niclausse et a1. 122235 1,830,324 11/1931 La Mont 122-39 1,972,052 8/1934 La Mont 122-235 2,800,113 7/1957 Kessler et al. 122235 KENNETH W. SPRAGUE, Primary Examiner. 

1. A WATER TUBE BOILER COMPRISING, IN COMBINATION: (A) WALL MEANS DEFINING A BOILER SPACE (1) SAID SPACE HAVING A NORMALLY UPRIGHT AXIS, AT LEAST A PORTION OF SAID SPACE BEING OF SUBSTANTIALLY HEXAGONAL CROSS SECTION; (B) A SOURCE OF A GASEOUS HEATING FLUID COMMUNICATING WITH ONE AXIAL PORTION OF SAID BOILER SPACE; (C) MEANS FOR WITHDRAWING SAID HEATING FLUID FROM ANOTHER AXIAL PORTION OF SAID BOILER SPACE; (D) A DISTRIBUTOR TUBE IN ONE AXIALLY TERMINAL PORTION OF SAID BOILER SPACE; (E) A COLLECTOR TUBE IN THE OTHER AXIALLY TERMINAL PORTION OF SAID SPACE, AND NORMALLY UPWARDLY SPACED FROM SAID DISTRIBUTOR TUBE, (1) SAID COLLECTOR TUBE AND SAID DISTRIBUTOR TUBE EACH HAVING SIX SECTIONS JOINTLY CONSTITUTING A SUBSTANTIALLY REGULAR HAXAGON OF TUBE SECTIONS, (2) SAID SECTION BEING ARRANGED CLOSELY ADJACENT SAID WALL MEANS AND SPACED FROM SAID AXIS; AND (F) A PLURALITY OF WATER TUBES IN A PORTION OF SAID SPACE AXIALLY INTERMEDIATE SAID TERMINAL PORTIONS, (1) SAID WATER TUBES BEING OFFSET FROM SAID HEXAGONS OF TUBE SECTIONS IN A DIRECTION TOWARD SAID AXIS AND COMMUNICATING WITH SAID DISTRIBUTOR TUBE AND WITH SAID COLLECTOR TUBE, AND (2) SAID WATER TUBES BEING ARRANGED IN THREE COLUMN,S EACH COLUMN INCLUDING A PLURALITY OF HEAT EXCHANGING UNITS EXTENDING IN RESPECTIVE PARALLEL AXIAL PLANES, (3) EACH HEAT EXCHANGING UNIT INCLUDING AT LEAST ONE OF SAID WATER TUBES, AND THE PLANES OF SAID CLOUMNS BEING OFFSET FROM EACH OTHER BY ABOUT 60* WITH RESPECT TO SAID AXIS. 